1. Field of the Invention
The invention concerns cosmetic compositions in the form of strips, patches, skin liquids, creams, gels or pastes which can evolve heat when in contact with moisture.
2. The Related Art
Heat-producing cosmetic compositions produce a very pleasant sensation. These formulations are friendlier than the cold traditional products applied to the skin. Considerable prior technology is available for generating warmth.
U.S. Pat. No. 3,250,680 (Menkart et al.) reports the use of finely divided solid adsorbent materials which are capable of exothermically reacting with water. Illustrative of these materials are silica gel, activated alumina and synthetic zeolites. U.S. Pat. No. 4,626,550 (Hertzenberg) discloses similar heating systems with improved versions of zeolite based on the presence of potassium ions as replacement for some of the sodium ions. A still further elaboration is found in WO 93/08793 (Kemp et al.) reporting on other exothermic agents reactive with water. These include kaolin, Fuller's Earth, china clay and bentonite.
A common problem with the known art is the requirement for very high levels of water reactive solids. Without a significant concentration of those solids, temperature increase will be relatively small. There remains a need for cosmetic compatible systems achieving much higher heat output per gram of heating agent. High levels of solid heating agents have the further problem of thickening the compositions beyond ready flowability.
Accordingly, it is an object of the present invention to provide cosmetic compositions adapted to be self warming which rely upon highly efficient heat generating systems.
Another object of the present invention is to provide cosmetic compositions adapted to be self warming wherein the heating agents are present at levels insufficient to prevent the product from easily flowing.
These and other objects of the present invention will become more readily apparent from consideration of the following summary and detailed discussion.